A stringer tang is a tab of metal that extends longitudinally from the end of a stringer. This tab is used as a reference datum and has a bolt-hole therein. The tang is secured to a reference point on a jig (which is a known datum with respect to a panel) and hence locates the stringer spatially in relation to the panel. The stringer tang itself allows the stringer to be bolted to and structurally supported by the jig. Thus, the stringer is located in the correct position in relation to the panel.
The stringers are then riveted or fastened to the panel whereupon the entire assembly is released from the jig by removing the panel plus the stringers from the jig. The tangs are then cut off and the areas around them are treated to remove any protuberances or rough edges. This is a time consuming and laborious process.